Primary objectives in this investigation of Best's macular dystrophy include; delineation of genetic and clinical characteristics including prognosis and natural history; determination of the diagnostic reliability of EOG ratios; search for genetic linkage; characterization of retinal function parameters; search for metabolic and basic genetic abnormalities; and exploration of possible therapeutic measures. Thus far, 16 pedigress of Best's macular dystrophy have been ascertained, containing 125 affected persons. Attempts will be made to study each of these individuals using the EOG and genealogical relationships as the primary means of detection and affected individuals will be studied further with fundus photography, fluorescein angiography, ERG's, and dark adaptation as well as by serial clinical examinations. All affected individuals will be followed annually with clinical examination and fundus photography to delineate the natural history and prognosis of this disease.